1. Field of the Invention
This invention pertains to a motor driven device for adjusting the inclination of motor vehicle headlamps.
2. Description of the Prior Art
Such devices are increasingly installed in modern motor vehicles to prevent the headlamps from blinding oncoming traffic when, for example, the motor vehicle is carrying a heavy load. In known mechanisms of this kind, the headlight is swiveled round a horizontal axis by means of a crank gear. In such mechanisms, the direction of rotation of the electric motor must be variable in order to provide that the headlight can be brought into the right position as quickly as possible without having thereby to pass through the dead position of the crank gear. Passing through the dead position can, under certain circumstances, result in a momentary directing of the headlights towards the oncoming traffic.
In a known device complying with this requirement, the operating switch has two mechanically coupled bridging contacts in two switching planes, through which the positive and negative terminals of the supply voltage source can be connected to one each of n stationary contacts, whereby n corresponds to the number of desired adjusting possibilities. These 2 n stationary contacts are each connected to a slide spring by means of a lead and cooperate with a switching disk connected with the motor shaft in a manner that is protected against torsion. The switching disk is provided on both sides with two contact paths separated from each other by insulation and provided with contact gaps. On each of these four contact paths, a slide spring resiliently rests. The slide springs are coupled in pairs and connected with the motor current supply lead. The electric motor is fed with operating current through these contact paths and the slide springs as long as the slide springs being applied to voltage will meet the contact gaps. Thus, it is ensured that the electric motor will be stopped in the right position by the switching disk which in connection with the slide springs forms positions switches.
In this embodiment, the operating switch is connected to the electric motor through 2 n leads. One pair of these leads conducts the motor operating current and therefore must have a suitable cross-section. Furthermore, the operating switch with two switching planes and 2 n contacts is of complicated design. Also, 2 n+4 slide springs are necessary to provide the position switches for stopping the electric motor in the right position. The production of switching disks provided with contact paths on both sides is relatively expensive.
DE-OS 2,637,326 teaches a circuit arrangement wherein the reversal of polarity of the voltage source and thereby reversal of rotation is not accomplished through a complicated switch disk. A reversing switch operating in dependence on the direction of switching is integrated in the operating switch. However, n+1 leads are still necessary between operating switch and electric motor. However, although the switch disk can be produced more economically, the construction of the operating switch is very complicated.